Pen



FIG. 1 is a perspective view of a pen showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a side view thereof, the other side being a mirror image of the side shown;

FIG. 4 is a rear view thereof;

FIG. 5 is a bottom end view thereof; and,

FIG. 6 is a top end view thereof.

The broken lines in FIG. 6 are included to show a portion of the pen that forms no part of the claimed design. 

CLAIM The ornamental design for a pen, as shown and described. 